Real Idea is the Divine Truth embedded in creation that pushes and governs creation from behind by the impulsion of Truth. You may call it the Law of Truth that governs all things. It is called Idea in the sense that it represents the secret truth held back in things. This secret truth or the Real Idea is encoded within everything and discloses itself or expresses itself progressively in its journey through Space and Time. You will find it in The Life Divine, especially in Chapter 14: The Supermind as Creator. It is the conscious Knowledge-Will that drives each element in creation, in their respective individual manifestation as well as in their relation to all other elements. The word that would come closest to it in Indian thought is Ritam or Rtachit.
[The Supermind as Creator: https://incarnateword.in/cwsa/21/the-supermind-as-creator]
Affectionately,
Alok Da
